Light-sensitive layer



Patented Nov. 7, 1933 LIGHT-SENSITIVE LAYER Maximilian Paul Schmidt, Wiesbaden-Biebrich, and Hermann Neuroth, Wiesbaden, Germany, assignors to Kalle & Co. Aktiengesellschaft, Wiesbaden-Biebrich, Germany No Drawing. Application January 5, 1932, Serial No. 584,902, and in Germany January 16, 1931 9 Claims.

The present invention relates to light-sensitive layers.

. Various processes have already been proposed for producing light-sensitive layers by means of azo components which render possible the preparation of negative copies. According to German specification No. 82,239, dated May 26, 1894, in the name of. I. G. Farbenindustrie Aktiengesellschaft, the decomposition product, which is obtained by exposing a diazo layer to light, is developed by means of a diazo solution so as to form a dyestufi. German specification No. 111,416, dated April 13, 1899, in the name of Marcel Schoen, and U. S. Patent No. 1,444,469, dated February 6, 1923, in the name of Gustav Kiigel and Heinrich Neuenhaus, disclose the use of diazo compounds which, on exposure to light, yield dyestuffs. In German specification No. 53,455, dated December 5, 1889, in the name of Adolf Feer, the reaction products obtained from diazo compounds and sulfites, i. e. the so-called diazo sulfonates are used together with alkali phenolate or an amine or a hydrochloric acid salt thereof. From all the light-sensitive layers prepared according to these known processes, negative copies are obtained after exposing the said layers to light under a pattern. These processes could, however, not hitherto be utilized in practice, inasmuch, as they posses certain drawbacks, such as, for example, a complicated method of use, unsatisfactory stability of the layers, the production of dull whites in the copies, etc. In U. S. Patent No. 1,760,780, dated May 27, 1930 in the name of Maximilian Paul Schmidt 5 and Wilhelm Krieger, it is proposed to employ layers of two or more diazo compounds for the preparation of light-sensitive layers having better stability.

Now we have found that very stable lightsensitive layers for the production of negative papers are obtained by applying a reaction product of a diazo compound and a sulfite, i. e. a socalled diazo sulfonate together with one or more coupling diazo compounds, on any base, for instance, paper, film, wood, cellulose hydrate foils or the like. Instead of applying the light-sensitive substances on any base it is also possible to impregnate such a base with the said compounds. In the new process it is likewise possible to employ diazo sulfonates from diazo compounds which easily decompose in a free state or produce coloured decomposition products, when the light-sensitive layers are stored, or again, which would react with the admixed diazo compound. The process according to the present invention is thus an essential improvement on that claimed in U. S. A. Patent No. 1,760,780.

When working according to the new process it may, according to requirements, be'preferable to use diazo compounds in the form of their sulfonates which in a free state have a strong coupling power. In particular, diazo sulfonates of the following formula:

wherein R stands for a benzene or naphthalene radical being substituted or not; and X stands for a metal group, are useful for the present process. The coupling diazo compound may be used as such or in form of double salts with, for instance, inorganic salts as cadmium chloride or the like,

It is also advisable to use as the coupling diazo compounds which are appliedtogether with the diazo sulfonates on any desired base, such compounds as yield good coupling decomposition products on exposure to light. The layers claimed herein may, if desired, contain additional substances such as are used in diazo-type printing. The new light-sensitive layers are rather stable and yield a negative copy from a positive pattern 30 or vice versa, when exposed to light under such a pattern. The formation of the picture probably takes the following course. The light decomposes the aromatic diazo compound capable of coupling in such a way that an azo component is formed. Simultaneously it acts upon the diazo sulfonate whereby the latter decomposes while yielding a diazo compound, capable of coupling. This diazo compound acts upon the azo component formed as described above, thus yielding a dyestuff picture, which can be fixed by washing out with water the undecomposed parts which were under the designs of the pattern. When the diazo sulfonate used decomposes rather easily, the reaction may occur in such a way that first the 5 diazo sulfonate is split into a coupling diazo compoundand this latter is at once decomposed into an azo component by the action of light. The azo component thus formed reacts then upon the coupling diazo component present in the layer I formula:

in 10 parts by volume of alcohol of 50% strength. After filtration the solution is applied in the usual manner on baryta paper. Upon exposure to light under a negative, brown positive prints are obtained which are fixed by -washing with water.

Instead of applying the solution on a base, it is also possible to impregnate a base therewith, for instance, a cellulose hydrate foil.

(2) 2.1 parts'of the sodium salt of l-benzoylamino 2.5 diethoxy -4-,d,iazobenaene-N-sulfonic acid of the following formula fi N SbaNa and 1.2 parts of the cadmium chloride double salt of 4-diethylamino-2-hydroxy-1-diazobenzene are dissolved, while gently heating, in 25 parts by volume of alcohol of 50% strength with addition of 5 parts by volume of butyl alcohol and 1 part by volume of glycerine. After the solution has been filtered, it is applied in the usual manner on baryta paper. On exposure to light under a negative, a brown positive copy is obtained which is fixed by washing with water.

(3) 20 parts of the sodium salt of 4-chloroanisol-2-diazo-N-sulfonic acid and 10 parts of the cadmium chloride double salt of 4-diethylamino- 2-hydroxy-1-diazobenzene are dissolved in 100 parts by volume of alcohol of 50% strength. After the solution has been filtered throughanimal charcoal, it is applied on baryta paper. On exposure to light under a pattern, a yellowishbrown negative copy is obtained which is fixed by washing with water. A

When using in the preceding example instead of the cadmium chloride double salt of 4-diethylamino-Z-hydroxy-l-diazobenzene, 8 parts of the.

sodium salt of 1-diazo-2-hydroxy-3-benzoic acid, yellowish-red copies are obtained.

We claim:

1. As new articles of manufacture, light-sensi tive layers containing as light-sensitive sub-- stances aromatic diazo compounds capable of coupling in mixture with a diazo sulfonate incapable of coupling, being stable and yielding a negative copy from a positive pattern and vice versa when exposed to light under such a pattern,

2. As new articles of manufacture, light-sensitive layers containing .as light-sensitive subof strong coupling power, in mixture with a diazo sulfonate incapable of coupling, being stable and yielding a negative copy from a positive pattern and vice versa when exposed to light under such a pattern.

3. As new articles of manufacture, light-sen sitive layers containing as light-sensitive substances aromatic diazo compounds capable of coupling in mixture with a diazo sulfonate incapable of coupling of the following formula:

I wherein R stands for a benzene or naphthalene radical, being substituted or not, and X stands for a metal group, being stable and yielding a negative copy from a positive pattern and vice versa when exposed to light under such a pattern.

5. As new articles of manufacture, light-sensitive layers containing as light-sensitive substances aromatic diazo compounds capable of couplingin mixture with a diazo sulfonate incapable of coupling of the following formula:

being stable and yielding a negative copy from a stances aromatic diazo compounds yielding, when exposed to light, decomposition products positive pattern and vice versa when exposed to light under such a pattern.

6. As new articles of manufacture, light-sensitive layers containing as light-sensitive substances aromatic diazo compounds yielding, when exposed to light, decomposition products of strong coupling power, in mixture with a diazo sulfonate incapable of coupling of the following formula being stable and yielding a negative copy from a positive pattern and vice versa when exposed to light under such a pattern.

8. As a new article of manufacture, a lightsensltive layer containing as light-sensitive substances 4-diethy1amino-2-hydroxy-l-diazoben zene in term of its cadmium chloride double salt in mixture with a diazo sultonate incapable of coupling of the following formula I t 05H;

aHl

z'i S OsNa being stable and yielding a negative copy from a positive pattern and vice versa wheniexposed to coupling 0! the following formula being stable and yielding a negative copy from a positive pattern and vice versa, when exposed to light under such a pattem.

PA BC. 

